Centrifugal pump



0st. 25, 1938. LA BOUR I 2,134,254

CENTRIFUGAL PUMP Filed Nov. 5, 1954 4 Sheets -Sheet 1 DISCH E VELO Y M 5m; TIPS 4/ Jnvenior ANGULAR TRAVEL X ELF/y Z (2 60111 0 SUCTION VELOCITY H. E. LA BOUR CENTRIFUGAL PUMP Get. 25, 1938.

Filed Nov. 5, 1934 4 Sheets-Sheet 2 k w? as hm RN! 3 J W r IF i 1 Q Q g Oct. 25, 1938. H. E. LA BOUR GENTRIFUGAL PUMP Filed Nov. 5, 1934 4 Sheets-Sheet 5 222/02 for.

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Oct. 25, 1938. H. E. LA BOUR CENTRIFUGAL PUMP Filed Nov. 5, 1934 4 Sheets-Sheet 4 r T r Patented Oct. 25;1938

UNITED STATES PATENT OFFICE 14 Claims.

The present invention relates to centrifugal pumps.

The chief object of the present invention is to provide a pump of high hydromechanical eflicien'cy and simple rugged construction.

A further object is to provide a pump which will produce a desired pressure over a wide range of delivery, i. e., outflow from the pump.

A further object is to provide a novel method of pumping whereby the desired pressure may be realized in a centrifugal pump over a wide range of delivery, i. e., outflow from the pump.

A further object is to control within the pump itself the distribution of pressure and flow, whereby flow restrictions in the intake and discharge passageways are eliminated and a great increase in volumetric and hydro-mechanical efliciency is attainable.

The specific embodiment herein shown is a multi-throat pump employing an open impeller. With the specific form of pump herein disclosed, I have been able to realize high efliciencies even in small capacities, with accompanying advantages of compactness, simplicity and low cost.

In the accomplishment of the aforesaid chief object, I construct the casing, impeller and discharge passageways in such form and proportions as to secure the desired velocities which are to be generated and the flow to be carried, with a high degree of streamline flow.

It is to be observed that if approximate streamline flow through the pump is to be attained, each functional part of the pump which has to do with flow must be coordinated with the others so that these elements, most of which operate in series with each other, will not interfere with attainment of efliciency of the whole.

The preferred form of pump which I shall herein describe and illustrate is an open /'impeller pump. It is a familiar fact that an open impeller pump will generally not operate at as high mechanical eiiiciency as a closed impeller pump, other things being equal. Open impeller pumps have certain advantages such as simplicity, lower cost, less tendency to clog up etc., and hence there is a real demand for a high efliciency low cost open impeller pump.

The chief reason for the lack of efllciency in pumps of the open impeller type I conceive resides in the fact that the water is carried idly in frictional contact with the side walls of the pump casing. I have observed that the liquid to be pumped must be moved radially and angularly in order to attain the desired velocity. But after it has traveled the required distance radially and angularly to attain the desired velocity, Iconceive that it should be promptly discharged. Now in order to produce the minimum travel angularly, the impeller must be coordinated in form, size and speed with the intake and discharge so that the liquid picks up its velocity in minimum angular travel and is then promptly discharged. This coordination of attainment of velocity and arrival at a point of discharge I term synchronism or synchronous operation. By coordinating syn-' chronous operation with the proper shape of the passageways I am able to develop efliciencies and outputs never before attained in comparable sizes of impellers or pumps.

The present invention embodies a new principle applicable to multiple throat centrifugal pump devices. 'I'hat principle, as will be explained more fully below, comprises the simultaneous control of distribution of flow and the development of pressure at the multiple discharge throats by internally regulating the ratio of angular travel to radial travel of the operating medium in the impeller inadvance of release into the throats. According to the best application of this principle each and every particle of fluid is free to flow into the pump, and is free to flow out of the pump without any flow restriction or any interruption except that each and every particle must in flowing through the pump pass through a definite angular travel at the periphery of the impeller.

There are at least four distinct features, which, according to the teachings of my pump, combine to produce the desired advantageous results in regard to efliciency, and output.

The first feature is the introduction of the water into the impeller. The second is the travel through the impeller. The third is the transition of the water from the impeller to and through the discharge throats; and fourth, the combining of a plurality of streams into the common discharge. According to the preferred form of the present invention the working fluid is free to flow into those parts of the impeller which are passing over the concentric portions, and in fact to every point on the periphery of the impeller, the blades being of negligible width compared to the width of the ports. But while the fluid can flow freely into the impeller, it cannot flow radially outward of those parts of the impeller which at any instant are passing over the closed or concentric portions. Neither can it flow out of any part of the impeller without first passing over the concentric portions or sealofl's. Radial flow at the periphery is stopped by these concentric portions or sealofls, and radial pressure is as angular travel occurs.

The working fluid which is at any instant pass- 4 ing or about to pass over a concentric portion is temporarily held against radial flow while angular travel occurs. Then, having been given angular motion and hence having acquired a predetermined inertia of motion, the working fluid is allowed to escape from the periphery of the impeller and be thrown or impelled through a throat which is suitably proportioned to the other characteristics of the pump, so that maximum velocity of the working fluid occurs at this point.

These throats lead through relatively long expansion passageways where velocity is gradually transformed into pressure. These long expansion passageways all lead to the common discharge outlet in parallel and, as for as possible, at the same velocity and at a small angle to each other, so as to minimize all shock.

The greatest difllculty with multiple discharge pumps as heretofore known has been the problem of equalizing pressure and flow around the im- .peller, i. e., at the various branches or passageways where liquid is intended to be discharged. Unless provision is made to prevent it, one part of the impeller and one throat will provide most of the discharge, and the remainder of the impeller and the other passageways allow useless work to be done'on the working fluid, with resultant loss of efliciency. The art heretofore has attempted to equalize the discharge, either by placing flow restrictions in the outlets, such as the so-called diflusers, or by placing constrictions in the inlets leading to the various parts of the impeller.

According to my invention, no restrictions are provided at either the inlet or in the discharge passageways. Both these passageways are preferably formed so as to provide maximum freedom to flow so that efliciency is not lowered. I secure control of distribution by the same means which insures adequate discharge, 1. e., by the concentric portions of the channel which insure the acquisition of adequate discharge pressure. This concept of free entry into the impeller-and free outward flow beyond the throats is, so far as I am able to determine, broadly new, and constitutes the introduction of a new principle into the art of moving fluid by centrifugal effect. The principle of my invention is independent of the working fluid. The invention is applicable not only to multiple discharge centrifugal pumps, but

s also to centrifugal blowers or fans operating on gases. The principle is also independent of the My: invention is broadly new as applied to open impellers or closed impellers, and for either liquid pumps or gas blowers or fans.

The results secured by my invention are not only greater mechanical or hydraulic efficiency, but much greater output from a given size of impeller and casing, and amuch wider range of deliveries at a, given head.

v The water must be twisted 0! the intake stream and begin its acceleration angularly and radially with minimum friction, shock and eddy currents,

"and my construction is highly eiiicient insecuring this effect; 7

With respect to the phase of acceleration of the water in the impeller, my invention aims to bring the water smoothly and with minimum travel to maximum velocity and immediately thereupon remove the water from further engagement with the impeller. As soon as the aromas water has had imparted to it maximum energy, 1. e., is brought up to full velocity, it is discharged irom. the working chamber. Any unnecessary travel particularly at maximum velocity results in friction losses and eddy current losses and detracts from both mechanical and volumetric efliciency. In the form of pump herein disclosed, three discharge throats are provided; This number may be varied, but'the desideratum is to have the water discharged as soon as it has reached discharge pressure or velocity, and not be carried angularly any further than necessary.

The preferred form of impeller blades of my invention are shown as substantially straight with the tip or end of the blade curved back only to the extent of avoiding the formation of eddy currents at the blade tips. I have employed absolutely straight blades with excellent eiflciency but there appears to be a whistling noise thatis undesirable. The straight blade brings the liquid to maximum velocity in the least angular travel and makes the least frictional contact with the water, and due to maximum acceleration of the.

liquid allows the use of more throats for the discharge.

In the three throat pump, the ideal action for maximum emciency and capacity is to have full pressure developed within substantially 120 degrees of angular travel, and the more nearly this synchronism is accomplished, the better will be the performance of the pump. This ideal may not always be attainable in production, but according to my preferred embodiment, it is closely approximated within the practical tolerances of commercial manufacture. I consider that the production of the synchronous operation above described is broadly new.

The number of blades is an important consideration. Theoretically, the space between blades should be relatively small, and the blades should occupy no space, but practical considerations require the blades to have suflicient body and strength to withstand mechanical service and corrosion. I have adopted eight blades with a three-throat pump as a satisfactory! working comprise. Too much surface or too great a number of blades is not desirable. The use of eight blades with three throats gives an excellent balance which makes it easy to keep the packing gland tight. In referring to balance I do not mean mechanical balance alone but both mechanical and hydraulic balance. a

At the important zone. where the wate emerges from the impeller and enters the throat, it has maximum energy, and here its treatment is most important. The impeller of my invention leaves the water stream with minimum disturbance. I promote this by a slight rounding or curving back the tips or ends of the blades. The object here is to provide, as nearly as possible, a smooth streamline flow of the slip between the blade end and the outgoing stream.

I am aware that blades with long trailing tips have been proposed for securing pressure increase, but the impeller. ofmy invention is designed for no such purpose, as the long trailing tip intended to secure higher pressure must be designed, I believe, to set up eddy. currents to realize such high pressure. My impeller has straight blades slightly modified.

areas,

with minimum opportunity to depart from streamline fiow. The expansion passageways of the pump of my invention extend peripherally about the pump for a considerable angular distance, and as nearly on the same radius as possible to each other. The chief direction of expansion is lateral, i. e., axial of the shaft.

This insures that first a high velocity stream does not discharge into a low velocity stream with consequent shock and friction losses, and, second, so that when two streams are brought into contact, that is at a very small angle at slow speed and with minimum differential in speed and direction.

I believe the coordination of the synchronous action of building up the velocity in a fraction of the circumferential travel with immediate discharge and streamline flow produced by proper proportioning of the cross sections of the passageways through the pump is broadly new.

A second and highly important object of my invention is to improve the mechanical structure of pumps of this character. Among the features provided to accomplish this object are the following:

1. An improved form of supporting and aligning bracket for coupling the pump casing to a suitable support, and to align the packing gland of the impeller shaft and the bearings of a supporting and driving shaft.

2. An improved form of assembly clamp for coupling the front plate to the pump casing to allow, conveniently, of any desired adjustment of the inlet and outlet relative to each other.

3. An improved and simplified form of packing gland and follower which keeps the pump shaft tightand makes servicing of the gland unusually easy.

4. "A novel form of combined mounting and cooling hub for the casing and packing gland.

Other and incidental objects and improvements will be apparent from the following detailed description, the drawings, and the appended claims.

Now in order to acquaint those skilled in the art with the manner of constructing and operating a device embodying my invention, I shall describe, in conjunction with the accompanying drawings, a specific embodiment of the same.

In th accompanying drawings, in which like reference numerals indicate like parts, Figures 1 to 6, inclusive, are diagrams to explain the operation of the pump;

Figure 7 is a side elevational view, with parts broken away, showing one specific pump of my invention with its drive shaft and mounting;

Figure 7a is a fragmentary section through the pin of the modified form of a gland follower arm;

Figure 8 is a transverse cross section taken on the line 8-8 of Figure 7;

Figure 9 is a front view, partly in section, of the pump with the cover or inlet plate removed;

Figure 10 is a section taken on the broken line Ill-l0 of Figure 9, looking in the direction of the arrows;

Figure 11 is a side elevational view of the impeller which is shown in front elevation in Figure 9; and

Figure 12 is a fragmentary section taken on periphery of greatest radial extent of the impeller,

it is conceivable that'minimum loss due to eddy currents, by providing the substantially streamlined fiow with an acceleration of the liquid, might be secured.

If,'in the usual single outlet pump, indicated in Fig. 2, this theorybe applied, then in order'to secure streamline flow with minimum idle carry of the liquid, the liquid should flow from the inlet E at the center to the tangential outlet F as a spiral stream. The velocity of inlet flow at the inlet E,should be a minimum, with maximum cross section, increasing velocity occurring through theconvergent or nozzle portion of the path as indicated-at B,.until maximum.- velocity is attained at A at the most constricted portion of the fiow, where the flow of the central part of the stream substantially leaves the tips of the impel er blades such as G. From the most constriated portion or highest velocity of flow, the liquid then should continue to flow with decreasing velocity through the expanding or divergent nozzle portion C leading 'to the discharge outlet F.

It will be seen, however, that if synchronism be thus attained, the rest of the periphery of the pump and the impeller is either idle or must carry water idly around the interior periphery represented by the dotted line H. Assume that in the case illustrated in Figure 2, the blades G of the impeller have brought the liquid from the intake E to the discharge port Whit .1 lies between the points I and J, to the desired velocity within 120 of rotation, that is, by travel from point H to point I. It can be seen that the impeller and pump casing could, theoretically, be capable of discharging three times the amount of liquid which the pump'is actually handling, as. per the diagram of Figure 2.

But another defect is now apparent in the pump if it be constructed in accordance with standard practice, and that is that the desired I progressive constriction in the cross section of the stream from intake to point of maximum velocity cannot be attained by-circumferential constriction. Hence, synchronism which I herein teach is not practically attainable in that manner. A further requirement which I teach is that the constriction of cross section to give true, or approximately true, venturi flow flow is choked more at the-central part of the impeller than it is at the periphery, where its velocity should be a maximum.

In Figure 3 I have illustrated diagrammatically and idealized, for the sake of clearness, the im pellerl and a development of the casing and passageways of the pump of my invention, this impeller having a multiplicity of blades mounted upon a shaft 2 which is preferably formed integral with the blades. The casing provides an inlet passageway E which opens into a pocket 3 in the impeller to facilitate the distribution of liquid from the passageway Eabout the entire must be secured mainly in an axial direction, i. e., by progressivelycircumference of the impeller. The casing defines an impeller chamber which, in cross-section, is shown by the outlines of the impeller I in Figure 3, thisimpeller terminating atthe most constricted part-of the outlet, as indicated by the reference character A, where the blade tips terminate. Beyond the blade tips the casing provides the divergent passageways CC. From this diagram it may be seen that the cross section of the passageways through which the liquid flows from the intake pipe Eto the discharge outlet is intended to follow the general scheme of the Venturi pipe shown in Figure 1, wherein the impeller blades accelerate the liquid from the larger cross section to maximum velocity at the minimum cross section, and from thence the liquid in an expanding passageway loses velocity and increases in pressure. a

An impeller such as I moving in an annular chamber with a continuous peripheral outlet will not give the desired efflciency or characteristics, one of the reasons being that the impeller will impart rotary motion to the liquid beyond the blade tips, and it is necessary, therefore, to provide vanes which serve first to limit the radial travel of liquid driven by the impeller to permit a delivery pressure to be built up', and, second, to stratify the flow so that each passageway or portion of the discharge flow will be conducted in orderly manner through an expanding channel. These channels, I conceive, must then discharge into a common outlet through a suitable junction, this junction being so arranged that the difference in mean velocity of any two adjacent streams, and the mean difference in direction of flow of the streams, is a minimum. Since the liquid, in going from the inlet pipe E to the discharge, follows in' general a spiral path, a number of discharge throats may roughly be determined by determiningthe angular distance through which the water must travel in order to take up the desired energy from the impeller. Thus if, as indicated in Figure 2, the design speed and size of the impeller, the shape of the blades and shape of the casing is such as to permit sumarranged at 120 apart on the periphery. There upon synchronisni with a completely fllledan active impeller will be attainable.

Multiple discharge pumps are known. It is known by pump designers that a centrifugal multiple discharge pump involves the difilculty of controlling the distribution of work as between throats. will be a tendency for one or more throats to rob the others and produce an unbalanced condition which renders the pumping characteristics unsuitable for general use, and which interferes with volumetric and mechanical efllciency to an extent which largely destroys the value of the design, I have conceived of the possibility of constructing a high efliciency multi-discharge port pump which, through the simple expedient of restricting radial flow of liquid in advance of each discharge port, will insure the functional independence of the sections of the pump and compel each section to develop the desired delivery pressure, and hence do its own share of the work. Since this control resides at the point where both radial flow and the development of pressure can be and are governed, the pump of shown as 120.

If no provision is made to cure this there my invention. requires no flow restrictions, inlet directors or outlet diffusers, such as have been employed in multi-throat pumps of the prior art. Also, my pump is thereby able to employ the streamline flow through Venturi-shaped passageways, as above described, without flow restrictions either on the inlet or outlet side. The result is that my pump operates, in a given size impeller, at superior efficiency.

In Figure 6 I have indicated how, in a three throat pump, the desired synchronism may beattained. The throat spacing, as abscissal, is The desired delivery velocity or pressure is indicated by the ordinates to be any desired value represented by 100%.

Taking into account the size (diameter) of the impeller; the shape thereof the shaft speed desired; the delivery required, and the density of the liquid to be pumped, it is possible to build up the pressure .within the angular distance allotted (120) so that the liquid arrives at the throat as indicated by line OM at the exact instant of attaining its full delivery pressure. If the proportions be slightly diiferent the delivery pressure may be developed before the liquid arrives at the discharge port, as shown by line 0L. Then the carry of liquid from L to M is idle or wastful carry of water at high velocity.

If the proportions be changed, as by providing 1 blades of greater curvature, the delivery pressure will not be attained until the liquid has been carried through a greater angular distance than the minimum between throats as indicated by line OPN. In such a design the most efilcient operation would be at a velocity or pressure corresponding to the height of point P above line OX. The pump could also deliver at higher pressure but at decreased efliciency, because of lack of synchronism. Were the blade formed sothat full delivery pressure were not attained until the liquid had been carried through 240 travel, as per line OSQ, then there would be two points at which. the liquid could be discharged, the first throat would tend to relieve the pressure at less pressure than is attainable at Q. Again the emciency is reduced because of lack of synchronism. The ideal condition of synchronous operation, together with proper shape of passageways for streamline flow andsmooth acceleration and deceleration of the liquid, provides maximum eiiiciency, and it is the object of the. present pump to embody the same.

In Figure 7 I have illustrated, in side elevational view, a specific embodiment of my pump alignment, as will be later described. The driving shaft section I4 and the impeller shaft 2 are coupled by a key I! which lies within telescoping splines formed in the respective parts, the impeller shaft having a reduced end or stud portion which its within an axial recess I6 in the adjacent end of the driving shaft section ll, a threaded rod or bolt II extending through the hollow shaft section It and being threaded into the end of the impeller shaft 2 and provided externally shaft section I, the coupling being in endwise with a tightening nut l8 to pull the shaft section I4 and the 'impeller shaft 2 into telescopic relationand in alignment, this being particularly facilitated by the sliding fit and the provision of the shoulder I6 at the junction of the stud or reduced portion of the impeller shaft with the full section thereof. This shoulder engages the end face of the driving shaft section I4.

The impeller shaft 2 is designed to be guided concentrically of the packing recess 26 which is formed about the shaft opening through the hub 2| formed on the main pump casing or frame I2. This hub 2| projects axially from the side wall of the pump casing or frame, and is provided with a flat, annular machined surface 22 which provides a clamping surface against which there is bolted a similar annular surface on a cooperating clamping member 23, which is preferably ring-shaped in form and provided with a cooperating clamping surface eng ing the surface 22. The hub 2 I is provided with an extending piloting flange -24 to facilitate the fastening of the hub member 2| and the clamping member 23, as by a series of studs 25. Cap screws may be employed instead of studs. The clamping member 23 and the flange 24 are preferably piloted together by interengaging .annular shoulders, as indicated at 26. A supporting pedestal 21 is adapted to support both the driving shaft sectionv I4, with its connected impeller shaft 2 and impeller I, and also to hold the pump casing or frame in proper alignment. This pedestal member 21 includes the base portion 26, the clamping member 23, and thesupporting arms 36-36 which support the pump by cantilever action.

\ These arms 36-36 are relatively thin, vertically disposed plates which merge into the clamping plate or slotted ring-like member 23 that is bolted against the flange 24 of the hub 2|. These arms 36, at their opposite ends, are formed inte gral with the central part of the pedestal member 21, which central part includes the aperturedshaft section or ring-like clamping members porting the bearing for the shaft section I4. The ring-like members 3|, 32 are 'formed at their lower ends integral with the base portion 26, the base portion 26 being hollow.

The shaft section I4 is supported at the bear- 3I', 32 for sup .ings 33 and 34,'these beirings being shown as ball bearings having the inner rings mounted on the I4 as by means of a shoulder on the shaft section, a clamping ring 35 for the bearing 33, and a similar clamping ring- 36 for the hearing 34. The outer rings are mounted in a cylindrical sleeve member or barrel31 which has extending flange portions at 36, 36 for cooperating with the split rings 3| and 32. Cap-members 46 and 42 are held by suitable bolts such as 43 and 44 against the corresponding ends of the barrel member 31 and hold the outer races in place. The outer race of the bearing 34 is held in place endwise to limit the axial travel of the shaft section I4 and hence of the impeller I in the pump casing I2. The outer race of the bearing 33 is merelyconflned circumferentially and is allowed to float in the axial directions.

The impeller shaft 2 carries a liquid slinger 45 which cooperates with the end cap 42 to prevent the travel of liquid along the shaft 2 into the bearings or into the junction between the two shaft sections. The barrel 31 may be provided with a suitable filling of oil or grease as through the plug 46, a drain plug 41 being provided at the rear.

It will be seen that the flanges of the barrel member are less in diameter than the opening through the slotted clamping ring 23 carried by the arms 36-36. The barrel member and the which a pin or key 52 .cumferential recess with which fork 66 being adapted bearings thus may be removed without disturbing the main body of the pedestal member 21.

The base 26 is provided with flanges upon opposite sides such as indicated at 46, suitable feet such as 46-46 being formed on the four corners :or mounting the base 26 upon a suitable surface The barrel member 31 and ring 32 are piloted together by registering grooves or keyways into may be disposed for accurate alignment and assembly of the parts.

While the ring members 3| and 32 are preferably split ard then clamped upon the flanges 36 and 36, the parts may be provided merely with a suitable concentric flt and bolted in place by overhanging flanges, if desired.

Within the axial packing recess 26 in the hub 2| is compressed upon the shaft 2 by a suitable gland follower 53 which flts within the axial recess 26 and is guided therein to compress the packing material 26'. This gland follower 53 is provided at its outer end with a recess adapted to receive packing material 54 and a secondary gland follower 55 seals the outer end of the gland follower 53 upon the shaft 2. The intermediate, or main gland follower 53 is provided with a cirthere communicates a lubricating pipe 56 (see Figure 8) to the outer end of which a compression grease cup is preferably connected. A follower ring 51 mounted on the shaft 2 is adapted to engage'the end of the secondary gland follower 55 and apply a yielding pressure to thereby to retain packing in the recess 26.

The secondary gland follower 55 may be split.

so as to be removable if desired. The ring 51 has a recess which embraces the end of the follower 55 and provides the necessary hoop strength for the outer end thereof, the inner end of the follower 55 being restrained in the recess in the outer end of the main gland follower 53. The ring 51 has a pair of notches (see Fig. 8)

into which are extended the short pins orstuds 56-56 of a fork member 66 formed on the lower or vertical arm 62 of a bell crank lever 63 which is pivoted upon a pin 64 extending loosely throuhg the bell crank lever and through the plates 36-36 and held in place as by cotter pins 65-65 (see Fig. 8). The bell crank 63 may be provided with an eccentric sleeve I26, held in 7 place by a set screw I 22 and being adjustable angularly by the hexagon head I23 to raise or lower the pivot about which the arm 62 swings.

-The horizontal arm 66 .of the bell crank' lever 63 is provided with a fork 66 at-its-outer end, this to receive the shank 66 of the eye-bolt 16 between the tines thereof. These tines 66 are notched transversely to receive the ends of the pivot bar 14 which, in effect, forms a I provide suitable packing material 20' whichthe main gland follower 53 knife edge bearing in the aforesaid notches. The

pivot bar 14 has'a central hole through which passes the shank of the eye-bolt 16 and a compression spring 15-bears upon the said pivot bar 14 and is adjustably stressed by the wing nut 16. The eye-bolt 16 is supported on a transverse pin 12 which passes through the plates 36-36 and is held against endwis displacement by the cotter pins 65-65.

To service the packing gland, the wing nut 16 is released to allow the bar 14 to be raised out of the notch'in the fork 66,- whereupon the eyebolt'16 may be swung about the shaft 12 to release the same from the horizontal arm 66 of the'bell crank lever 63. If

desired, the trans- 15 usually n. The lever 88, however, is preferably removed to provide access to the gland and follower. This is done by withdrawing one of the cotter pins 88, pulling out the cross pin 88, unhooking the pins 58 from the notches in the ring 81, whereupon the bell crank lever 88 may be withdrawn, making the entire gland readily accessible from the space between the two plates or arms 88-88. Since these plates 88-" do not extend substantially below the center line of the packing gland and its shaft 2, the lower half of the gland is quite open at all times, and with the lever 88 out of the way a high degree of accessibility is afforded. In Figures '1' and 8 it will be observed that the lower edge of the arms 88-48 lies above the top of the shaft 2.

If it is desired to remove the impeller i the pressure on the packing gland may be released by throwing the eye-bolt 18 and its spring 18 and cross bar 14 out of register with the fork i8, whereupon the pressure upon the packing is released. The shaft section Il may then be uncoupled from the shaft 2 by loosening the bolt i1 or the nut 18 and pullingthe' impeller l, with its shaft 2, to the left as viewed, in Figure 1. The

liquid slinger 48 is relatively loose uponthe shaft 2 and may readily be'stripped oil of the end of the same, and the shaft 2 thereupon pulled through the packing gland and out of the open side of the pump frame or casing II, the inlet plates i8 being removed.

If it is desired to remove the bearings, this may readily 'be done by releasing the barrel 81 from the rings 8i and 82. Where it is desired to remove the barrel and the shaft section it with the pump, the studs or bolts 25 which hold the pump to the pedestal member 21 are loosened, the bell crank 88 is pulled out of the way, the barrel 81 is released from the rings 8| and 82, and thereupon the shaft section ll with the barrel may be pulled out through the clamping ring 28 which islarge enough to permit these parts to pass. It will be observed that the clamping plate or ring 28 is preferably cut away at the bottom (see Figure 8). This is done to facilitate assembly and also to prevent liquid of a corrosive character from attacking the clamping plate or ring. Obviously the ring 28 need not be so cut away. 7

The hub 2| is provided with an annular water passageway surrounding the main packing for cooling the same. Water may be introduced into this cooling chamber or water jacket either from an external connection, such as the delivery side of the pump, as through a pipe 1.1, the water then being discharged through a passageway 18 to the runner chamber near the hub thereof, or the circulation for the water jacket may be entirely internal, by providing an inlet passageway to the water Jacket from a point where the pressure is greater and a discharge at a point where the pressure is less, such points existing at different radial distances within the casing. v

The hub and supporting construction which I have shown may be varied. In fact, the pump casing I! may be supplied with a solid hub II, as shown in Figure 10, forv mounting in a split clamp carried by the arms -48 instead of the clamping ring 28. Such form of hub and split clamp is shown in my Patent No. l,993,999, issued March 12, 1935. The gland and follower construction and the bearing construction are preferably ofthe form shown in Figure 7.

Referring now to Figures 9, .10 and 11, the casing or main pump frame comprises a'substantially fiat wall 88 which has a Junction with the hub Ii or II, as the case may be, the said hub having acentral'opening for the impeller shaft 2 and an axial recess 28 about the same for the main packing. This end wall may be suitably reinforced by radial ribs or flanges, if desired. The

end wall 88- has a finished interior surface 82 forming the side of the runner channel. The inner surface of the wall 88 is relieved from said machined surface 82 to the center. This obviously, is optional. This end wall 88 is substantially disc-shaped and its outer periphery merges into the volute portion and into the outlet connection or nomle 88 in the following manner. The nozzle or outlet is provided with a clamping flange 85. The wall 88,which defines the adja-'-' cent part of the outlet, is joined to a circumferen-' tial wall 81 and the junction of these two walls forms a cut-off 88 defining the termination of one discharge port 88. The wall 81 is curved about the axis of the impeller shaft for a short distance as a cylinder then continues on an increasing radius and its innersurface defines for a short distance the cylindrical bottom of the runner channel then continues as a passageway communicating with the discharge port 88. The wall 81 continues in spiral form to form the outermost wall of the volute 88 and finally ends up at the flange 88. The end of the discharge port 88 is defined by a spiral.wall 8|, the forward end of which 82 forms a cut-off for the discharge port 88. This wall 8| eontinuesfor a short distance as a cylinder then proceeds in spiral form, defining betweenitself and the outermost wall 81 a spiral passageway of gradually increasing cross section, said wall 8i finally terminating at 88 substantially in a feather edge. On its inner side the wall 8| forms for a short distance the cylindrical bottom of the channel then continues as a passageway for the discharge port 84. The discharge port 84 terminates at the edge 85 of another spirally disposed wall 88 which wall 86 forms, between its outer surface and the inner surface of the wall 8|, a gradually expanding passageway 81 which merges beyond the feather edge 88 with the discharge of the passageway 88. The wall 88 extends between the passageways 8i and 81 for and 81, which have previously merged.

, Each of the three sections of the channel is thus provided with a cylindrical portion which is concentric with the impeller l, and of a radius 'which except for mechanical clearance is substantially the same as that of the impeller. This cylindrical portion represents the angular carry ,of water to build up delivery pressure. The walls or vanes 8| and 88 are relatively thin platelike portions with the trailing ends gradually tapered to approximate feather edges for leading the adjacent streams together smoothly. The thickness of the vanes is not the important feature, but the shape should be such as to form, in conjunction with the'cooperating walls in each case, a gradually increasing passageway to provide a smooth deceleration and increase in pressure. Sharp changes in direction or velocity in the passageways are to be avoided.

It will be observed that the axial "depth or width of the blades of the impeller I is relatively small as compared to the diameter of theoutlet opening or nozzle 88.. The outlet opening, 84 is 'preferably circular, as is the flange 88. The 7 spective passageways is secured chiefly by increasing their axial dimensions as they lead from the periphery of the impeller to the outlet opening 84.

Thus, by reference to the width-of the passageway as indicated in Figure 10 it will be seen that the axial dimension or width of the channel in which the ends of the blades of the impeller run is shown by the position of the wall 00. The width of thepassageway 91 is indicated by the position of the wall I00, and the width of the passageway 90 is indicated by the position of the wall' IOI, all in Figure 10. Thus, by securing the flare, or increase in cross section mainly by increasing the axial dimension, the casing of the pump may be made more compact and of substantially less size in a radial direction.

It will be observed that in, the embodiment illustrated in Figure 9, there are three discharge ports leading to the common outlet 84 substantially without constriction. Between the outlet ports 89, 90 and 94 there are concentric cylindrical portions or walls with which the tips of the blades have substantially only mechanical clearance. These cylindrical bottom portions of the channel in conjunction with the impeller 2 form radially restraining walls whereby each of the three sections ofthe pump isat all times functionally substantially closed oil from the other sections by the impeller blades whether these blades be parts of an open runner or of a closed runner. The blades are preferably spaced apart a distance which is substantially not greater than the extent of the radially restraining portions, so that at least one blade is always in registering relation with respect to a substantially cylindrical wall of the bottom of the channel for each of the three parts of the pump. These radially restraining portions to that extent act functionally as sealofis. It is to be understood that the functional eifect of predominating'angular travel followed by the functional eifect of predominating radial travel in proper synchronous relation is the characteristic sought. Variations of form are not important so long as the above characteristic is predominant. have more than mechanical clearance, the effect is not lost so long as the liquid which is carried on the cylindrical channel walls is responsive to the blades in partaking of angular carry to acquire discharge velocity or pressure in advance of release radially into the discharge ports.

The'shape of the impeller blades is also capable of considerable variation, so long as the above characteristic synchronous action is maintained.

A draining opening I02 through the wall 9| and a draining opening with a plug I03 through the wall 8'! permit liquid to be draine from the pump to avoid injury by freezing.

The main pump casing or frame I2 is provided with a cylindrical recess which terminates .at its end on the machine surface 82, this cylindrical recess being of such diameter as to permit the insertion of the impeller I from the left as viewed in Fig. 7. This recess is machined out to provide a cylindrical surface at I04 (see Fig.7) A short flanged neck I05 is formed on the left-hand end wall as viewed in Figures '7 and 10 for the connection of the cover or inlet member I3. This inlet member comprises an annular flat wall section I06 with a machined surface parallel to the machined surface 82' to form the front side of the runner channel. A cylindrical wall portion Even if the blade tips or cylindrical flange I01 fits within the-bore I04, and a radial flange I08 extends out beyond the flange neck I05, a suitable packing gasket being interposed between the flange I and the neck I05. A split clampingring I00, having its inwardly extending flange adapted to be disposed backof the flange on the neck I05 registers with the outer periphery of the flange I00 so that studs or bolts IIO may clamp the split flange I09 and the flange I08 together. The split flange I00 is preferably split at two or more points, so that the parts thereof may be readily disposed in position to hold the parts remo'vably together. The

inner radial margin of the annular plate I06 merges into the converging conical wall II 2 and this wall H2 in turn merges with the diverging wall II3, the junction of the two walls H2 and H3 forming the maximum constriction of the i inlet passageway. The outer part of the wall 3 is provided with a suitable clamping flange I I4 for connection to a corresponding flange on the inlet pipe.

The impeller I, which is shown in dotted lines in Fig. 7 and in full lines in Figures 9 and 11, is formed in two somewhat dissimilar parts, but these'partsare so formed mainly for convenience in manufacture rather than for difference in operation. Tliat is to say, considering the outline of the impeller I as viewed from the side (see Figures 7 and 11) this outline is the result of practical consideration rather than theoretical considerations. Theoretically considered, the impeller might better be shaped according to the strict converging Venturi shape shown at the point B in Figure 3, but for practical reasons the impeller is divided into two parts, namely, the extending blade ends IIG, the axial allel planes for convenience in manufacture, .and the wing portions III which take the form of truncated conical portions. In brief, the impeller of Figure 11 is the practical embodimentof the theoretical shape shown in Figure 3. The arms II6 are substantially oblong in cross section except for the reinforcing ribs II8 upon the backs thereof, and at the edge facing the intake the wings III are cut away at the center to provide .ingly. In other words, the conical wall II2 follows quite closely, with clearance only, the taper of the Wings 1.

The present pump is designed to impart to-the liquid operated upon the necessary energy for delivery pressures within approximately 120 of angular movement of the liquid. There is always some slip of the water or liquid with respect to the impeller, but obviously, eihciency is promoted by reducing such slip. In tion I-have three discharge ports about the internal periphery of the runner channel and the open impeller has eight blades or arms tapering in axial depth from a maximum at the center, or adjacent the center, to a minimum at the tips. The impeller is thus balanced mechanically and also hydraulically because the eight arms do not permit simultaneous register with the three ports. It will be observed that the blade tips 0 are given a backward curve. This is done mainly to the present construcfaces of which lie in paravoidnoises and eddy currents at the point where the blade leaves the departing water at high velocity. If the blades could leave the water without slip, curvature on the ends of the blades would be substantially ineflectual and all that would be required would be to give the blades a smooth, tapered end for withdrawing the same out of the current of water. As a practical-matter, the blade ends must have sumcient substance or material mass to provide the necessary strength to sustain the stress of driving the liquid, and to sustain some degree of corrosion.

, The axial recess indicated at 3 in Figure 3 allows the water to enter the impeller without sub stantial constriction. Constriction at this point would mean that the velocity of the liquid would be unduly high, and this is undesirable.

. The double taper of the inlet member provides -a control which cuts down losses in the'intake throughexcessive rotation or helical travel of the water in the intake pipe. At the point where the water takes up angular motion instead of longitudinal motion there is a rapid change in direction and velocity. .The throat at the inlet, as indicated, tends to limit the formation of uncontrolled fiow and eddy currents at this point, which is conducive to an increase inefficiency of the device. The form of pump herein shown carries out the thought of Venturi -shaped passageways and streamlined fiow to 'a high degree, even though the parts are not strictly in conformity to theoretical curves as indicated in Figures 1 and 3.

- Figure 4 indicates diagrammatically the included blocks of water K lying between two adjacent vanes or arms of theimpeller, and C indicates the divergent discharge passageway lead ing from the port which lies on the interior periphery H of the. casing,-this port being defined.

by the opening between points I and J. However, the actual flow of water is not radial, bntspiral, as indicated'in Figure 5. The passageway comprises the spiral convergent portion -B leading to the point of greatest restriction at A and dis-- charging therethrough through the divergent dis- .charge passageway C. In other words, the flow of water, according to the diagram 5, is a transient phenomena occurringwithin the pump, the ratios of cross section at any point in the diagram of flow shown in Figure 5 being such as to allow the water to enter the impeller at a relatively low rate of flow and then gradually to be accelerated until the narrowest part of the passageway is reached, at which point the impeller withdraws from action.

In the diagrams no attempt is made to show the, actual dimensions or actual proportions, but

' merely to indicate the character thereof.

Figure 6 indicates the action of three streams of liquid according to the diagram of Figure 5. Assume that the entire peripheral distance is indicated by the line O-X and the radial extent of the impeller by the vertical line O-Y. The distance represents 360 and, for a pump of three discharge throats, the velocity of the water in increased from the center to the periphery through a certain angular carry, in this case approximately 120, as above discussed.

Whereas I indicate 120 as the optimum, it is to be understood that the angular travel of the water may be greater than. 120 for a three throat pump, but it will be seen that if the travel be greater in angular extent than is nec: essary to have the desired energy imparted thereto, such excess travel introduces unnecessary friction losses and reduces the volumetric eiilciency of the pump. As a pocket between blades is rotated from-one discharge throat to the next discharge throat, the pocket is kept substan-- tially closed at its outer end, so that liquid cannot escape freely until it comes into register with the next pocket. Now at the same time, itis to be understood that the rate of movement v of the pocket, while thus closed and carried between throats, is such that the desired discharge pressure (or centrifugal force) is developed. 10 The attainment of the desired pressure (or centrifugal force) and the arrival at the discharge position or port must concur to secure the desired synchronism. The diagram of Figure 6 is intended to convey the above thought. The physi- 5 cal structure which secures it is shown in Figure 9. The cylindrical bottom part of the channel between the point of cutofl 82 and the next port N illustratesthe feature of functionally closing oi! the pocket between adjacent blades The water contained in that pocket at the instant illustrated in Figure 9 (assuming the impeller to be rotating) is being moved angularly substantially without radial travel. It is thereby acquiring kinetic energy and developing centrifugal force.

Then when the pocket opens to the discharge passageway 94, the water from the pocket is released smoothly at high angular velocity, 1. e., wit maximum possible discharge pressure.

-Release of the water in a pocket results in increase in the radial flow as compared to the angular travel. This means that the water is being delivered radially through the pocket with less work done upon it by the impeller. This is illustrated by the pocket in Figure -9 containing the as reference numerals 9| and 94. This produces. an inertia of radial fiow which assists in providing discharge. However, such radial flow begins to diminish as the pocket passes over the next cutoif as at 9!. pocket passing over the cylindrical portion following cutoif 95 substantially" loses radial flow and takes up angular motion to develop kinetic energy (centrifugal force).

It will be observed that the sole obstruction to flow from the intake l3 through the impeller .to the outlet 84 is that introduced by the cylindrical bottom parts of the channel. No inlet restriction for equalizing flow into the impeller, or outlet flow restriction or diffuser for equalizing 5o discharge as between discharge throats, is necessary. This principle of compelling the water to pass through a definite angular path, substantially without radial flow, as a means for securing distribution of work and a desired delivery pressure over a wide range of fluid deliveries.

is broadly new.

I am aware that it has heretofore been proposed to provide a centrifugal pump with multiple outlets, and I do not claim my invention so n broadly as to include merely multiple outlets.

No one, so far as I am aware, has provided in a multiple outlet centrifugal pump definite portions of the channel in which the water is functionally confined radially for the purpose of aequiring centrifugal force in advance ,of release into the succeeding discharge ports. Such radial confinement and development ofdischarge pressure forms the solemeans for controlling distribution of fiow through the pump. I believe it is broadly new to secure synchronous opera-' tion of a pump as above-described. It is also broadly new I believe to coordinate the synchronous operation with the streamline flow secured by varying thecross section of the passageways Then the water in the 40 I to approximate Venturi shaped conduits of flow.

Also I am aware that ithas been proposed to employ impellers with long trailing tips to cooperate with specially shaped multiple throats with the object of attaining high discharge pressures, but my pump is not concerned with that structure or'mode of operation.

Tests of the present pump in comparison with single outlet pumps, employing as nearly as possible the same shape of impeller, show conclusively the improvement in efficiency and head which may be obtained through the use'of the present invention; A sample pump embodying the present invention equipped with 9%" diameter impeller, 1" in width, was able to deliver substantially the same volume and head as a comparative pump of the type which I have marketed und'erthe designation #25-DW, having an outlet located at only one point on the periphery; andprovided with a diameter impel1er;1"'in width,

The pump of the present invention designated as #30- QW in comparison with the considerably larger #25--DW showed markedly superior eflici'ency. The following is a comparative table of results:

: 1 7 50 R. P. M.

1 inch wide 9% 1 inch wide 10% inches diameter inches diameter G. P. M.

Hd. Efi. Hd. E6.

104 as 106 54. a

I do not intend tobe limited-to the details specifically illustrated and described, particular-.

between said connections having unobstructed communication with said inlet connection, said chamber comprising a relatively narrow channel on the inner periphery of the chamber having a series of substantially tangential discharge ports substantially equally spaced about the periphery of the channel, there being substantially concentric arcuate bottom wall portions for the channel between discharge ports, the runner chamber having a relatively great depth axially at the inlet connection tapering in depth toward the channel and merging therewith to produce a passageway for liquid flow which passageway is convergent in cross section toward the discharge ports, said discharge ports having independent passageways leading in parallel to each other to the outlet connection, said passageways being separated by spirally disposed walls, said walls terminating in relatively thin edges to lead adjacent streams together with minimum shock, said passageways increasing in cross section from the discharge ports to the outlet connection and being free of flow restrictions, said runner chamber and said discharge passageways providing in effect a plurality of separate Venturilike flow paths extending in parallel relation of the vanes axially inlet connection to provide for relatively free -from the inlet connection to the outlet connecentry of liquid into the impeller and to prevent undue inlet velocity.

2. In a centrifugal pumping device, a casing provided with an axial tubular inlet connection and a substantially tangential tubular outlet connection, said casing providing a runner chamber freely communicating with both said connections, said chamber comprising a relatively narrow runner channel on the inner periphery thereof, said channel having a plurality of substantially tangential discharge ports disposed substantially equidistant about the periphery, there being substantially concentric arcuate bottom wall portions for the channel between discharge ports, said chamber having a relatively great depth axially at the central part and tapering in cross-section to merge with the runner channel and the outlet ports to provide in effect a converging passageway leading to each of the discharge ports, said discharge ports having relatively long spirally arranged overlapping discharge passageways free of flow restrictions and having a junction in the tubular discharge connection, said passageways being separated by relatively thin walls one of which terminates within the outlet connection said passageways progressively increasing in cross crease being provided mainly by increase in the axial dimension of the cross section, said runner chamber and discharge passageways defining a plurality of Venturi-like flow paths extending in parallel from the inlet to the outlet, and an open runner in said chamber,,said runner having a 'plurality of vanes substantially greaterin number than the number of ports substantially to equalize the effect of said vanes upon the fluid flow through the ports, said runner having a depth corresponding to the dimensions of the runner chamber, and having an axial recess registering with the inlet connection to provide relatively free entry of liquid into the runner and to limit the inlet velocity.

3. In a pump of the class described, a casing comprising two chief parts, said parts consisting of a body portion and an inlet portion, the body portion comprising a back wall, a series of integral spiral walls and end walls defining outwardly tapering discharge passageways between them, a tubular outlet connection forming a common junction for the outer ends of said passageways, and said casing having a cylindrical recess which terminates on the inside of said back wall, the margin of said recess having a short coupling neck, said inside back wall having an annular smooth surface forming the side of a runner channel, said inlet portion comprising a cover plate having a cylindrical portion fitting within the cylindrical walls of the recess and having an overhanging flange for attachment to said coupling neck, an axially disposed inlet connection providing an inlet opening for said cover plate,

inlet opening, said tapering discharge passage- 75.

rality of substantially tangential discharge ports and a substantially concentric peripheral wall in advance of each port forming a continuation of the cylindrical wall of said recess.

4. A centrifugal pump comprising a casing having an inlet, a runner chamber provided with a runner channel and a plurality of discharge throats and an outlet, and an open runner in said chamber with blades having their tips extending into said channel, substantially concentric walls between throats forming radial boundaries for water in parts of the impeller, said casing and runner providing a plurality of Venturishaped passageways between. said inlet and. outlet, with the blade tips and throats disposed at substantially the point of maximum constriction in said passageways, said runner having blades of relatively little curvature and being adapted to be operated at a rotatlve speed which will carry the water over said substantially concentric walls synchronously to discharge velocity and in register with each one of the throats.

5. In a centrifugal pump, a casing comprising an impeller channel, said casing having an axial inlet and a peripheral discharge connection, a series of tapered passageways'leading without flow restriction from the common outlet connection to ports opening into the channel, an impeller in the casing running in the channel, functionally effective sealoff portions in the bottom of the channel between adjacent ports over which sealoif portions full discharge pressure is developed, said impeller having blades extending from the central part of the casing to the bottom of the channel, the angular spacing between blades being not substantially greater than the angular extent of the sealoff portions of the channel, whereby each section of the pump is functionally sealed off at all times from adjacent sections by interposed blades of the impeller, the blades being relatively thin at their tips to avoid obstructing the ports, the blades being greater in number than the ports and the inlet connection opening without flow restriction into the central part of the impeller.

6. In a centrifugal pumping device, a casing having an impeller channel comprising peripheral substantially concentric walls at the bottom thereof, discharge ports opening through said substantially concentric walls at a plurality of substantially equidistant points, a volute having a common discharge outlet, relatively thin vanelike walls providing tapered discharge passageways terminating in the volute, an impeller having blades running in said channel, the ends of the blades being of small angular extent having substantially only mechanical clearance with the concentric portions of the bottom of the channel, said substantially concentric portions being of an angular extent at least as great as the angular distance between the ends of adjacent blades of the impeller, said concentric portions, in cooperation with the rotating impeller, insuring delivery pressure at each of the ports and controlling the distribution of flow of fluid between the respective ports and forming the sole flow restriction through the pumping device.

7. In a centrifugal pumping device, the combination of a casing having an axial inlet and a discharge manifold leading to a common outlet connection, an impeller chamber within said casing, said impeller chamber comprising a channel, the bottom of which channel has angularly spaced substantially concentric wall portions with discharge ports therebetween, said discharge ways terminating at their inner ends in a pluports being connected through unobstructed expansion passageways of outwardly tapering form leading in parallel to each other to the manifold, an impeller in said impeller chamber having blades the tips of which have substantially only mechanical clearance with the said substantially concentric portions of the channel, the blades of the impeller being spaced apart angularly by a distance substantially not greater than the distance subtended by said substantially concentric walls, whereby the sections of the pump between adjacent concentric portions are peripherally functionally closed off from each other at all times by the impeller blades the concentric portions in cooperation with the rotating impeller constituting independent parallel pumping sec tions which at their inlets communicate freely with each other and with the axial inlet at the central part of the impeller, and communicate freely with each other on the discharge side of the manifold beyond the expansion passageways.

8. A fluid moving device operating on the centrifugal principle, comprising a rotatable impeller having vanes and a casing enclosing the same, said casing providing a central inlet for fluid permitting free and unobstructed access of the fluid to the central part of. the impeller from which the fluid can flow outward to the periphery of the impeller, the casing comprising multiple throats leading to a common discharge through expanding passageways which are free of flow restrictions and which direct the fluid streams in parallel at small difference in direction or velocity relative to each other, said casing having sealofi portions functionally closing off the periphery of the impeller registering with the same to cause the fluid to be impelled with a high ratio of angular travel to radial travel whereby ade-- quate delivery pressure is insured in the fluid when it arrives in register with the throats.

9. A fluid moving device operating on the centrifugal principle, comprising a rotatable impeller having multiple vanes the inner parts of which are substantially radial and the outer ends of which are curved back, the central part of the impeller providing a chamber opening freely into the space between vanes in the impeller, and a casing enclosing the impeller, said casing providing a central inlet freely opening into said chamber in the impeller, said casing comprising multiple throats leading to a common discharge through expanding passageways, which passageways are free of. flow restrictions and which reduce the velocity of the fluid streams and bring them together all in the same direction relative to each other andat relatively small differences in pressure and velocity, said casing providing concentric portions functionally closing off the periphery of the impeller overlying the same for short distances in advance of the respective throats to cause the fluid to be impelled with a motion which comprises a high ratio of angular to radial travel in advance of reaching the discharge throats, whereby adequate delivery of pressure and flow is insured at each throat.

10.- In a centrifugal pumping device, a casing comprising an open central inlet and a runner channel defined laterally by side walls and defined peripherally in part by relatively thin vanes of approximately uniform thickness and of generally spiral form, between which vanes are formed outwardly tapered discharge passageways, adjacent passageways being arranged to discharge substantially in parallelism with each other to join smoothly into a common discharge stream.

11. In a centrifugal pumping device, a casing comprising a runner channel defined by side walls and defined peripherally by relatively thin platelike vanes, the inner ends of the vanes being concentric to define the bottom of the channel and the outer ends of the vanes extending spiral- 13! to define between them spiral passageways of increasing cross section to permit gradual reduction of velocity of fluid discharged therethrough, adjacent passageways being arranged to dis-v charge substantially in parallelism with each other to join smoothly into a common stream.

12. In a centrifugal pumping device, the combination of an-open multibladed impeller comprising relatively thin radially extending arms, a

casing comprising a runner channel for receiving the blades of the impeller, the casing having side walls defining the sides of the channel and having thin platelike vanes, the inner ends of. said vanes being concentric with the impeller for an angular distance not substantially less than the angular distance between impeller arms, 'the outer ends of said'vanes extending spirally about the axis of the impeller, the opposite surfaces of said vanes leading toward each other at the end at a small effective angle to bring the streams of fluid on opposite sides of a vane smoothly together.

13. The combination of claim '12 wherein the casing has an axial inlet freely opening into the central part of the impeller and a volute terminating in generally tangentially disposed dis- 'charge neck, one of said vanes terminating within said volute and one of said vanes terminating within said neck.

14. In a pumping device, a runner and a casing comprising a single continuous inlet for fluid into the runner, a runner channel and a volute surrounding the channel, said channel having a pair of, adjacent discharge throats and expanding passageways separated by,v a thin vane the inner endof which is substantially concentric for a short angular distance to define the bottom of the channel between throats, and the outer end of which vane is spirally disposed in the volute and terminates therein.

' HARRY E. LABOUR. 

